Automatic telephone system



Jan. 30, 1923. I 7 1,443,645

-W. T. POWELL. AUTOMATIC TELEPHONE SYSTEM.

FILED FEB. 18. 1920. 4 SHEETSSHEET I TIP anus INVENTOR WINFRED T POWELL.

BYJ

74 ATTORNEY Jan. 30, 1923.

W. T. POWELL AUTOMAT c TELEPHONE SYSTEM.

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4 SHEETS-SHE-EY 4 W. T. POWELL AUTOMATIC TELEPHONE SYSTEM.

FILED FEB. 18,1920.

. Jan. 30, 1923.

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INVENTOR WINFRED T POWELL ATTORNEY i rs WINFRED T. PO'WELL, OF ROCHESTER, NEVT YORK, ASSIGNOR TO THE STROMBERG- CARLSON TELEPHONE IIIAN'UFACTURING- COMPANY,

A CORPORATION OF NEW] YORK.

or ROCHESTER, NEW YORK,

AUTOMATIC TELEPHONE SYSTEM,

Application filed February 18, 1929. Serial N0..359,68 4.

To all whom it may concern:

Be it known that I, WVINFRED T. PowELL,

a citizen of the United States, residing at Rochester. in the county of Monroe and State of New York, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone systerns, and more particularly to telephone systems employing automatic switching in establishing a conversational connection between the calling and called subscribers.

It is the purpose of the present arrangement to provide means whereby the talking connection is extended through the operation of the trunking switch individual to each of the lines. This result is achieved by the use of relatively simple registers for storing the designation of the wanted. line, which thereupon operate to cause the calling and called trunk selecting switches to complete a connection.

F igs. 1, 2 and 3 of" the drawings when placed in the order named diagrammaticall represent a portion or the telephone system in which the portion of Fig. 1 above the dotted lines. represents the operating circuits of one line switch or trunk selecting switch. herein designated. the calling line.

switch. while the portion oi the drawing at the bottom of Fig. 1 below the dotted lines. diagrammatically represents the operating circuits of a second line switch or trunk selecting switch of a line herein desig nated the called line. The portion of Fig. l hctween the dotted. lines represents what are herein called link circuits or trunk circults.

it the upper lett. hand cornerot' Fig. 2 there are shown the control relays individual to one of the link circuits previously mentioned. At the center portion of Fi and 33, there is shown within the dotted rectangle. an allotter which functions to select idle link circuits in consecutive order. At the bottom of Figs. 2 and 3- il16ll are v hown within the two dotted rectangles. devices herein referred to as the tens register and the units register, and when taken tocalled are necessary to care Fig. 4 shows the circuits of the register sender modified so that the group of ten multi-contact relays may be replaced by a multi-brush rotary switch.

In the system herein disclosed there are one hundred lines which have access to any one of ten link circuits. Five senders, each provided with a tens and units register cooperate in the extension of telephone calls,

and as soon as a telephone connection 15.

completed, these register senders revert to common use. By reference to Fig.1, it

will be noted that the line switch'or trunk selecting switch individual to each line, is provided with twenty-five contacts. Five of these contacts lead to the register senders, and ten of these contacts are connected'to the outgoing end of a link or trunk, while the other ten contacts are connected to the incoming end of the trunk or link 'clrouit. it will 'be seen that on the initiation or a call, the line switch individual to the calling line selects any one of five senders if idle. T he calling subscriber thereupon operates his dial sender to transmit impulses corresponding to the designation of the wanted line. These impulses are stored up in the registers of the register sender and when a number isthus stored up, the line switch of thecalled line is started to operate and continues to advance its brushes until the incoming end 01 a previously allotted link circuit located. There-u on the sender is released'and the calling line switch. hunts for the outgoing end of the same link circuit. The allotter then advances to assign another idle trunk for the use of the next calling line. In this brief description of the system no mention. has been made of the ringing or busy sigal operations, but

these will take place as will be hereinafter pointed out.

The structure of the line or trunk selecti c allotter and registers and other pr gross rely operable switches employed in the system may be substantially similar to that disclosed in the patent to Clement l,lfl7.153. patented August 11. 1914. The number of brushes and sets of contacts with which these brushes co-operate vary in numher in the different switches as will appear by reference to the drawings. As herein disclosed the operating circuits of the line switch are arranged so that this switch remains in engagement with the trunk or link circuit last used. It will be understood, however. that a switch which advances to normal or restores to normal may be emploved without departing from the spirit of the present invention.

It is believed that the invention will. best be understood by tracing the method of establishing a connection from a calling substation, such as A, to a called. substation. such as that designated B. lVhen the calling subscriber at A removes his receiver from its switchhook, an operatingcircuit is closed for the line relay LR, from grounded battery, lower windinp of this relay, coutinuity contact and spring; 5 of the cutoff relay CO. through the substation circuits oi the calling subscriber. continuity spring and contact (3 of the cut-off relay to ground. The line relay LR attracts its armatures and thereby completes an operating circuit for the motor magnet MM of the trunk selecting switch individual to the calling line. The operating circuit of the motor magnet hill extends from grounded battery, resistance, back contact. armature and winding of the motor magnet MM. conductor T. inner-most armature and front contact of the line relay LR, conductor 8. continuity spring and contact 6 ot the cut-oil relay to ground.

Under the control of this last described circuit, the motor magnet MM continues to advance the brushes of the lino switch until the sender test brush of the line switch engages the test terminal of a link circuit connected to an idle sender. As soon as the sender test brush locates such an idle sender, a circuit is closed for shunting the motor magnet MM and for operating the cut-off relay CO. Such circuit extends from grounded battery, resistance, back contact and armature of the motor magnet MM. upper winding of the cut-oil relay CO. conductor 9. upper-most armature and trout contact of line relay LR. left hand armature and back contact of slow releasing relay 1O sender test brush 11. and since it has been assumed that the first idle sender located by the sender test brush 11 is that sender individual to the test contact 12 and test conductor 13, conductor 14, back contact, armature of relay 15, conductor 16, brush 1''? of the units register in its normal position. conductor 18, brush 19 ot the tens register in its normal position, left hand contact and armature of the slow releasing relay 20 and back contact and armature ot' impulse relay IMP to ground. As soon as the motor magnet MM is thus short circuited. it ceases to advance the switch, and the cut-oft relay CO When operated discon nects the line relay LR from the line so that this relay thereupon tie-energizes and extends the calling line through its upper arniatures and continuity springs to the tip brush 21 and ring; brush 22 of the line switch.

VVhon the cut-oft relay CO is operated, it closes a locking circuit for itself from ground through its lower winding and in multiple therewith a circuit from ground. left hand winding of relay 10, armature and front contact of the cut-oil relay CO, through the holding brush 23, holding contact 24, holding conductor 25, back contact and armature of relay 33. and relays 10 and 15 are operated in this circuit. and relay 15 is held operated in series, and relay 10 in multiple with the cut-off relay CO. The relay 15 attracts its armatures and at its right hand armature and front contact closes a circuit completed from ground. left hand armature and back contact of relay 139. Front contact and armature of relay 15. conductor 1 5, and winding); of slow releasing relay 2G to grounded battery. The relay 26 is operated and prepares a substitute energizing; circuit for the relay 15 inde pendent of the outer right hand armature of relay 38.

As soon as the calling subscribers line is extended through to the brushes 21 and 22 which at this time are in engagement with the contacts 27 and 28 an energizing circuit is completed for the impulse relay 1MP of Fig". 2. This circuit extends from ground. through the leitt baud winding; of relay :MP. conductor contact 27. and thence. over the circuit previously dcscribed over brush 21 to the substation A. and then to ring brush 22 and contact 28. conductor 30, right hand indine of: relay IMP. conductor 31. lower winding: of resistance unit 32 to grouinled l'iattery. The relay .TMP is energized in this circuit. and attracts its armature to close an ope; ting: circuit for the slow releasing relay 20. The sender now in condition to receive the innpulses cor responding: to the tens designation oi the wanted subscribefis line. The callingsuhscriher thereupon operates his impulse sender to transmit impulses corresponding to the called subscribers line. Let it be assumed that this number designation is 89. The calling; subscriber first sends eight impulses caused by eight interruptions ot the circuit just described to the impulse relay l in turn initiate the operation of the iz ed line switch. In like manner when and second senders are idle, the nation stored up in the third sender will become effective to bring about the cornplctiou of a call.

It is assumed that the allotter is standing in a position to designate an idle link circuit under which assumption the relay 46 is operated in a circuit traceable from ground, right hand winding of this relay, conductor l7, inner-most upper front con tact and armature of relay 26, conductor as, outer armature and continuity spring 4-9 of relay 39, back contact and armature of relay 50, back contact, armature and winding of the motor magnet Mdl l of the allotter, and upper winding of the resistance unit 32 to grounded battery. The relay 46 on operation closes a locking circuit for itself -from grounded battery, through its left hand winding, front contact and armature, conductor 51, upper-most front contact and armature of relay 26 to ground. As soon as relay 46 is operated, it interrupts the holding circuit of relay 26, but this last mentioned relay is slow releasing, so that the holding circuit for relay 46 is held operated for a short time. While relay 45 is operated, it extends a circuit from ground, its inner armature and front contact, conductor 52, register brush 34-, its contact 35, conductor 53, multi-contact relay to grounded battery. The relay 5% is energized in this circuit and closes its ten contacts. Simultaneously a second circuit is closed from ground, inner armature and front contact of relay 46, conductor 55, left hand winding of relay 56, units register brush 41, now in engagement with contact 42, conductor 57, closed contact 58, conductor 59, contact 60 and armature of the cut-off relay C of the wanted line B, conductor 61, and upper winding of slow re leasing relay 62, conductor 72, and winding of relay 71 to grounded battery. The re lays 71, 62 and 56 are operated in this circuit. The relay 56 completes a locking circuit for itself from grounded battery, winding of the motor magnet MM of the units r gister. its armature and back contact, 17, right hand winding, front contact and armature of relay 56, conductor 63, winding of relay fi l, allotter brush 65, back contact and armature of relay 6'7, and back contact and armature-cf relay 68 to ground.

The relay 46 has also completed a circuit from ground, its outer armature and front contact, right hand winding of relay 50 to grounded ba tery. The relay 50 attracts its armatures and closes a locking circuit for tself from ground. armature and front contact of relay 71, which is operated at this time as has been described, left hand winding of relay 50, brush 116 of the allotter, conductor 117, winding of relay 103 to grounded battery. The relay 103 when operated closes an energizing circuit from ground, its lower-most armature and front contact, winding of relay 88, and resistance to grounded battery. The relay 88 attracts its armatures and thereby closes a break point in the holding circuit of the called line switch.

As soon as the relay 62 attracted its armatures, it closed a circuit for the line relayLR' of the called line from grounded battery, lower winding of this relay,upper-most front contact and armature of relay 62, uppermost back contact and armature of cut-oil relay CO, to ground over conductor 59. As soon as the line relay LR attracts its armatures, it closes a locking circuit for itself from grounded battery, its lower winding, upper-most front contact and armature of relay 62, upper-most back contact and armature of cut-off relay CO, conductor 61, inner-most front contact and armature of relay 62,10wer-most front contact and armature of the line relay LR, lower-most continuity spring and contact of cutoff relay CO to ground. When the line relay LR operated, a locking circuit is closed for the relay 62, from grounded battery, winding of relay 71, conductor 72, upper winding, front contact and armature of relay 62, conductor 73, lower-most front contact and armature of line relay LR to ground at the continuity,

springand contact of relay CO. The operation of the line relay LR prepares an o 3- crating circuit for the motor magnet Mil of the called line switch or trunk selector switch. This circuit is traceable from grounded battery, resistance, back contact, armature and winding of the motor magnet MM, conductor 74, lower-most front contact and armature of line relay LR, continuity spring and contact of cutoff relay CO to ground. Under the control of this circuit the called line switch or trunk selector advances its brushes 75, 76, 77, 78 and 79 until the trunk test brush 79 which is now effective because of the closures of the lower contact and armature of relay 62 locates the idle trunk link that has been designated by the allotter switch. When a designated trunk line is located, a circuit is closed from grounded battery, resistance, back contact and armature of the motor magnet MM of the called line switch, lower winding of the cut-oil relay CO, conductor 80, inner armature and front contact of line relay LR, lower armature and front contact of relay 62, trunk test brush 79, contact 81, conductor 82, allotter brush 83, conductor 84, front contact and armature of relay 64 to ground, which circuit functions to stop the switch and operate relay C0. When the cut-off relay CO is operated it causes relay LR of the called line to (lo-energize and closes a circuit for itself from ground, through its upper windlng, inner upper front con tact and armature, conductor 85, brush 75,

contact 86, conductor 87, through contact, and armature of relay 88, winding of relay 67 to grounded battery. The cut-off relay CO and relay 62 are locked operated in multiple, and the relay 6'? is energized in this circuit. The relay 67 attracts its armatures and at its left hand front contact and ar1na ture closes a circuit from grounded battery, resistance, winding of the ringing relay RING, front contact and armature of relay 67, back contact and armature of relay 68 to ground. Relay RING attracts its armatures and closes a ringing circuit from the ringing machine 90 which is common to the exchange, upper winding of the trip relay, right hand front contact and armature of the ringing relay, conductor 91, contact 93, ring brush 76, through the bell at the called substation, tip brush 77, contact 92, conductor 9%, low resistance left hand front contact of relay BIN-G, inner right hand armature and front contact of relay 6'? to ground. By reason of the low resistance last mentioned a current is induced in the circuit including conductors 108 and 109,

leading to the calling substation with the.

result that the calling subscriber hears a tone indicating that the wanted party is being signaled. Ringing current is intermittently applied to the called subscribers circuit un til the called subscriber responds by removing his receiver from its switchhook, whereupon the trip relay TRIP attracts its armatures and at its upper armature short circuits the ringing relay RING. At the lower armature and front contact of the trip relay, a locking circuit is closed through its lower winding, armature and front contact, armature and bacl: contact of the ringing relay RING, inner right hand front contact and armature of relay 67 to ground.

When relay 67 was operated it opened at its left hand armature and back contact the circuit for holding the relays 16% of Fig. 2 and 56 of Fig. 3 operated. With the relay 64 tie-energized, the round potential for stopping the line switches associated with the allotted link circuit is now transferred from the test circuit of the called trunk selecting switch to that of the calling trunk selecting switch. When relay 56 deenergizes. it opens the circuit which has been holding the sender holding relay 1.5

energized. and also the relays CO and 10 an the first named relay immediately retract their armatures, but the slow releasing relay 10 has a holding circuit prepared for will be described. The relay CO upon tie-energizing disconnects the brushes 21 and 22 of its line or trunk selecting switch from the sender which it has previously seized, and the calling line is again connected to its line relay LR, causing'this relay to attract its armatures to operate-the busy relay 71..

When the circuit to the brushes 21 and 22 of the called line switch is opened, the impulse relay IMP tie-energizes and shortly afterward the slow releasing relay 20 re-. tracts its armature to completea self-interrupting circuit for the motor magnet Mid of the tens register, its armature and'back contact, brush 19 in its 01? normal position, back contact and armature of, relay29, bacl; contact and armature of relay Hill? to ground. The motor magnet MM continues to advance its brushes until brush 19 reaches its normal contact, whereupon the operating circuit just described is interrupted. A circuit is now closed for restoring the unitsregister, this circuit being described from grouno, armature and back contact .of relay IliiP, armature and back contact of relay 20, brush 19 in its normal position, conductor 18, brush 1'? in its off normal position,-bac k contact, armature and winding of the motor magnet MM of the units register .to grounded battery. Under the control of this circuit the units register is advanced until it reaches its normal position. Relays 33 and 39 are 'deenergized because the releasing grount jat relay IMP short circuits them. I

\Vith the line'relay LR operated the motor magnet MM of the calling line switch advances its brushes to seize the other end of the link circuit with which thecalled line switch is in engagement. During this sec.- ond operation of the calling line, switch, the testing operation is under the control .of the trunk test brush 97, since the relay 10 was locked energized after its previous hol.d ing circuit was interrupted by the relay 56. A substitute holding circuit for the relay 1 0 is immediately completed by the re-ener gization of the line'relay LE andrnay be traced from grounded battery, winding .of relay 71 at the extreme right of 2, conduc-tors 7 2 and 98, right hand. winding of relay 10, its inner right handfro nt contact and armature, inner front contact- .of the line relay LR, conductor 8, continuity spring and contact 6 to I ound, When allotted link is reached, the motor maget MM is shunted by a circuit from grounded battery, resis. ance, back .contactand armature .of the motor magnet h FM, upper winding of the cut-offrel ay', conductor 9, upper armature and front contact of relay LR, left hand armature and front contact of relay 10, brush 9?, test contact 99, conductor 100. allotter brush 9.5, back contact and armature .of relay 64. to ground. The cut-off. relay is ener ized in this circuit and attracts its armature to complete a holdingcircnit for itself from ground. its lower winding, and in multiple therewith a circuit for relay 10, its iower winding. front contact and armature of relay Cf], 130

holding brush 23, contact 101, conductor 102, inner armature and front contact of slow releasing relay 103, winding of relay 1 .0 to grounded battery. As soon as the cut-ofi' relay again attracted its armatures it connected the calling line to brushes 21 and 22 and closed a circuit including both sides of the calling line and both windings of the battery feed relay 104i. This relay is now operated and attracts its armature to close a substitute energizing circuit for the relay 103 and thereby shunts the relay 50, causing it to de-energize. When the relay 110 at tracts its armature, it closes a circuit from ground, right hand armature and front contact of the relay 100, conductor 106, allotter brush 107, back contact, armature and winding of the motor magnet MM of the allott and upper winding of the resistance unit 82 to grounded battery. Under the control of this circuit the motor magnet MM advances the allotter brushes one step and if the con tact 108 individual to the next link circuit is busy, the motor magnet MM will continue to advance its brushes until an idle link circuit is found.

Talking battery for the calling subscriber is supplied through the windings of relay 104, while talking battery for the called subscriber is supplied through the windings of the relay 68.

In the foregoing description it was assumed that the called line was idle. It will now be assumed that the called line is busy under which condition the cut-off relay CO individual to this line will have its armatures attracted so that when the multi-contact relay 54 is operated, the conductor 59 extended to the called line switch circuit will be open at contact 60. The relays 62 and LR of the called line cannot be operated due to the fact that this contact 60 is open. The relay 67 therefore cannot operate and will therefore not close the circuit to energize the ringing relay RING. Since the conductor 59 is open at the cut-oft relay C0 of the called line at the moment when relay 46 is operated, no energizing circuit will be closed for relay 56, consequently no holding circuit will be completed for the sender holding relay l5, and it will be de-energized. The cut-off relay C0 of the calling line will also be de-energized and re-ccnnect the calling line to its line relay LR, whereupon the motor magnet MM of the calling line switch will advance its brushes to the link indicated by the allotter. As soon as this link is reached, the motor mag net is again shunted and the cut-off relay CO energizes over a circuit traceable from grounded battery, resistance, back contact and armature of the motor magnet MM of the -nallii'ig line switch, upper winding of the cutoff relay CO, conductor 9, upper armature and front contact of line relay LR,

left hand armature and front contact of relay 10, trunk test brush 9?, contact 9, conductor 100, allotter brush 95, back contact and armature of relay 64 (now deenergized), to ground. The cut-oil relay on attracting its armatures connects the line to its brushes 21 and 22, and thereby coinpletes a circuit for the battery feed relay 104:. This last named relay continues the operation of the slow releasing relay 103, which in turn controls the release of the calling switch. l Vhen the cut-off relay is operated, it closes a locking circuit for itself and in multiple therewith a circuit for the left hand winding of relay 10. armature and front contact of relay CO, holding brush 23, contact 101, conductor 102, inner front contact and armature of relay 103, winding of relay 110 to grounded battery. Relay 110 attracts its armatures for a purpose to be described. Since the called line was engaged its line switch brushes are not moved into engagement with the trunk link indicated by the allotter, and therefore the called holding relay 6'? will not be operated. Under these conditions mitted from the busy machine BZ, left hand armature and front contact of relay 110, right hand back contact and armature of relay 67, condenser, conductor 108, contact 107, brush 21 through the substation circuits, brush 22, contact 106, conductor 109.-

ight hand winding of relay 104 to battery: The calling subscriber on receiving the busy signal knows that the called line cannot be reached, So that he then replaces the receiver on the switchhook to effect the release which will now be described.

In the present system the releasing means are so arranged that the calling subscriber effects the release of his line switch and the called subscriber effects the release of the line switch individual to his line. hen the calling subscriber replaces his receiver on its switchhook, the battery feeding relay 104; of Fig. 2 releases and shortly afterward the slow releasing relay 103 tie-energizes. W hen relay 103 retracts its armature, the holding circuit serially including the relay 110 and the relays 10 and CO is opened permitting these relays to release. At the upper armatures and front contacts of the relay CO the brushes 21. and 22 of the calling line switch are disconnected from this line so that the brushes of this line switch may remain in en gagenient with the link just used.

When the called subscriber replaces his receiver on its switchhock. his battery feeding relay 68 releases its armature and shortly afterwards the slow releasing relay SSretracts its armaturev lVhen relay d eenergizcs. it opens the holding circuit iueluding relays 67. CO and 62, and these relays ale-energize. At the lower armaturcs and front contact of relay CO, the brushes a busy tone is trans-- 7 6 and 77 of the called line switch are disconnected from this line. The called line switch also remains in engagement with the terminals of the link last used. It will be noted that the test conductor 106 leading to the allotter is connected to a busy potential. either at the front contact and armature of relay 110, or at the front contact and armature of relay 68 as long as either calling or called subscribers are holding this trunk circuit. As soon as the relay 67 de-energizes, it opens the locking circuit of the trip relay TRIP, and this relay restores to normal. v

If the called subscriber restores his receiver on its switchhook before the calling subscriber attempts to effect the release, the relay 68 will de-energize as before described, but there is still an operating circuit for the slow releasing relay 88 at the lower-most front contact and armature of relay 103. Under these conditions the slow releasing relay 88 is de-energized by reason of a shunt circuit extended from grounded battery resistance, upper contact and armature of relay TRIP still energized, back contact and armature of relay 68 to ground. When relay 88 is thus de-energized, the holding circuit including the relay 67 is interrupted and the called line switch is made ready for the next call in the manner previously described.

The present arrangement is so arranged that if either the calling or called subscriber does not replace his receiver on its switchhook when the other party to the connection has released, a busy tone is transmitted to the subscriber maintaining the connection. If the calling party restores his receiver to its switchhook the relays 104-, 103 and 110 will be de-energized in the'mannerprevi-' ously described, at which time the circuit is closed from the busy device BZ. armature and back contact of relay 110, outer right front contact and armature of relay 67, over conductor 91 to the called subscribers line. and conductor 91. If the calling party maintains the connection after the called party has released, relays 103 104 and 110 will be held energized while relays 68, 67 and 88 will be de-energized. Under these conditions a busy tone will be transmitted from the busy device. left hand armature and front. contact of relay 110, back contact and armature of relay 67, conductor 108 to the calling substation conductor 109, and winding of relay 10 1 to grounded battery.

It the subscriber B at substation 89 desires to establish connection to subscribe-r A. whose station is designated 88., shown at the upper left hand corner of Fig. 1. the subscriber at station 89 seizes an idle sender whereupon the tens register will advance eight steps. and the units register will also be advanced eight steps under which conditions the relay 5 1 (Fig. will again be energized, but this time its contact 119 will be efi'ective to extend the starting circuit 1.18 to the line relay LR and relay 10 of the substation 88. The remaining operations will be effective in a manner similar to that previously described.

At the lower left hand corner of Fig, there is shown an operators telephone. In the ordinary use of the present system this operators telephone is not necessary. However, if the calling subscriber fails to operate his dial within a reasonable time, the signal lamp 12 1 burns steadily and the operator by throwing her listening key LK will connect her telephone set to the calling line to ascertain the number of the wanted line. Thereupon she operates her dial 119 to intermittently close a circuit from ground over conductor 120 contact of the listening key, conductor 121, armature and front contact of relay 20, back contact and armature of relay 83, winding of the motor magnet MM of the tens register to ground. Under the control of this circuit the motor magnet MM advances the brushes of the tens register to store up the tens designation of the wanted line. The relay 1MP is held energized all during this time over a circuitincludinga. calling subscribers line, and the relay 20 is held energized at the armature" and front cont-act of this last named relay. The operating circuit for the relay 36 extends from grounded battery, winding of this relay, left hand front contact and armatureof relay 20 to ground over conductor 121. The relay 36 is held operatedduring this series of impulses, but at the termination thereof retracts its arn'iature to bring about the energization of the switching relay 33, whereupon the-impulses transmitted over the conductor 121 are transmitted to the inotor magnet of the units register. When the subscriber dials or the operator throws key LK, relay 123 operates and locks itself operated to extinguish lamp 124. The remaining operations take place in the manner previously outlined.

The operators telephone set also becomes effective if it is desired to omit the dial impulse senders from certain of the substations. Under these conditions the. calling subscriber on removing his receiver from its I switchhook, will thereby cause his line switch to seize an idle sender similar to'that shown in Figs. 2 and will be assumed that the sender of these figures has been seized. The impulse relay 1MP will be op erated over conductors 29 and 30 and will attract its armatures to close an operating circuit for the slow releasing relay 20. This last named relay attracts its armatures and at its inner right hand armature and front contact closes a circuit from ground overconductor 122, armature and back contact of relay 123 to the operators signal 124. Since the lamp burns steadily, the operator knows that she should attend to the call and she throws her listening key and requests the wanted number. She thereupon operates the dial 119 as previously described to complete the wanted connection. The operation of the key, LE, energizes relay 123 which looks itself and puts out the lamp.

In the modifications shown in Fig. 4- the group of ten multi-contact relays, common to the exchange, has been replaced by an eleven brush rotary switch. ll ith the exccption of this substitution and of slight changes in the circuit of the t ns and units registers, the remainder of the system as well as the mode of operation remains unchanged and it will thereiiore not be necessary to describe the manner in which the calling line switch seizes idle sender, or how the wanted number is stored up in this sender, or how the called and calling line switches then seize the allotted trunk, and how the signaling and releasing functions are performed. After the tens and units registers have been set, their relays EMF, 2(), 33, 1:3, 39 and 26 will be h d operated, and it the extended starter 1" is in condition to permit the call stored on the sender of Fig. 1 to be completed, the relay 16 will then be operated to bring about the completion of call. llelay 46 is one 'zed in a circuit closed. from ground. its 1 k it hand winding, inner upper front contact and armature or relay 26, outer armature and continuity spring of switching relay 39 to battery over conductor 125. Relay 16 attracts its airnatures and at its left hand armature and front contact closes a locking circuit over conductor 51 to ground at the upper armature and front contact of relay 26. At the inner righthand rmature and front contact of relay 4-6, a circuit is closed through the motor magnet 127 of the eleven brush switch, its armature and back contact, and resistance to grounded battery. Under the control of this circuit the motor magnet 12'? advances the brushes of its switch until the test brush 112 engages the contact 113 which test contart is determined by the setting of the units register at which time the motor magnet 12'? is shunted by a circuit now closed from grounded battery, resistance. test brush 112, test contact 113, contact and brush 41-1 of the units register, winding of relay 11 i, out r right hand front Contact and armature of relay 16 to ground. The relay 11% is operated in this circuit and at its armature and back contact opens up the holding circuit for the slow releasing relay 26, which in turn shortly afterward interrupts the locking circuit of the relay 4'6, but before relay as is de-ene gizcd the starting circuit for the caller. line switch is closed to ground over conductor 59, contact 111, brush 128, conductor 129, contact and brush 3 1 of the units register, left hand vinding oi relay 56, front contact and ar-' mature of relay 114 to ground. The remaining operations o1 the system including the operation of the called line switch and the release or the sender are accomplished inthe manner previously outlined.

What I claim is:

1. In a telephone system, a plurality of telephone lines, trunk selecting switches each having fixed contacts, movable wipers co-operating therewith and individual op erating means for said wipers, said telephone lines terminating in said movable wipers, a trunk circuit common to said lines terminating at fixed contacts in said switches, means for causing each trunk selecting switch to seize one end said truna when its associated line originates a call, and means for causing each or" said trunk selecting switches to seize the other end or" said trunk circuit when its associated line is called.

2. in a telephone system, a plurality oi? telephone lines, a trunk selecting switch individual to each of said lines, said trunk selecting switch being provided with fixed contacts, sets of Wipers co-operating therewith and individual operating means for each set or wipers, a plurality oi trunk cirruits common to said telephone lines, both ads of each trunk circuit terminating in "d contacts of each trunk selecting switch, and means for actuating said trunk selectin switches to seize a trunk circuit in competing telephone calls.

3. In a telephone system, a plurality of telephone lines, a trunk selecting switch. individual to each of said lines, said trunk selecting switch having sets of fixed contacts, sets of movable wipers co-operating therewith and means individual to each switch for operating its set of wipers, a plurality of trunk circuits, each trunk circuit having its ends conductively separated but inductively connected together, the ends each of said trunk circuits terminating -:-:ed contacts of said trunk selecting in switches, and means for operating said trunk selecting switches in completing a call.

in a telephone system, a telephone line. a trunk selecting switch individual to said line, said trunk selecting switch being no vided with fixed contacts, movable contacts co-operating therewith and separate operating means for each set of movable contacts. said telephone line terminating in .aid movable wipers, a trunk circuit termi nating at two points in the fixed contacts oi? said switch, and means for advancing said trunk select s itch to one point when said line orig'nates a call, and means for advancing said trunk selecting switch to the other point when. said telephone line receives a call.

5. In a telephone system, a plurality of telephone lines, trunk selecting switches for said telephone lines, each of said switches having fixed contacts, movable wipers 'cooperating therewith and individual operating means for said wipers, said telephone lines terminating in the movable wipers of a trunk selecting switch, a plurality of trunk circuits common to said lines and terminating in said fixed contacts, an allotter for assigning trunk circuits for use, means for causing each trunk selecting switch to seize one end of an allotted trunk circuit when its associated line originates a call, and means "for causing elach trunk selecting switch to seize the other end of the allotted trimk when its associated line is called.

6. In, a telephone system, a plurality o'l telephone lines, a' trunk selecting switch for each of said lines, a plurality of trunk cir; cuits andv a plurality of sender circuits terminating in each of said trunk selecting switches, a sender connected to each of said circuits for storing up the designation of wanted lines, means for variably setting. said sender in response to impulses transmitted over its associated sender circuit, and means operative in response to the setting of said sender for causing the trunk selecting switch of the wanted line to extend the connection.

7 In a telephone system, a plurality of telephone lines, a trunk selecting switch individual to each of said lines, a plurality of trunk circuits and a plurality of sender circuits terminating in each of said trunk selecting switches a sender connected to each of said sender circuits, an allotter for assigning trunk circuits for use, means for causing the trunk selecting switch of a calling line to seize an idle sender, means for variably setting said sender in response to impulses transmitted over its associated sender circuit, means controlled by the setting of said sender for causing the trunk selecting switch individual to the wanted line to seize an allotted trunk, and means for extending the calling line to the allotted trunk.

8. In a telephone system, a plurality oi telephone lines, trunk selecting switches having fixed cont-acts and'mo'vable wipers in which a telephone line terminates, a pluralityof trunk circuits terminating in said fixed contacts, both ends of each of said trunk circuits terminating in each ot'said trunk selecting switches, and means for causing two trunk selecting switches to seize a trunk in completing a connection between two telephone lines.

9. In a telephone system, a plurality of lines, a progressively movable rotary step by step line switch vtor each of said lines, a

plurality of trunk circuits;;both.ends of each of said circuits terminating in each of said switches, and means to operate two rotary line switches to seize a trunk circuit in completing a connection between two telephone lines.

10. In a telephone system, a plurality of telephone lines, a trunk selecting switch for each line, a plurality of trunk circuits terminating in said switches, an allotter for as signing trunks for use, means controlled by the allotter to cause a trunk selecting switch of the calling line to seize an allotted trunk, directively controlled means for initiating the operation of a trunk selecting switch of the called line, and means controlled by said allotter for causing said last mentioned trunk selecting switch to seize said allotted trunk circuit.

11. In a telephone system, a plurality of telephone lines, a trunk selecting switch individual to each of said lines, a plurality of trunk circuits and a plurality of senders common to said telephone lines, means for causing a trunk selecting switch individual to acalling line to seize an idle sender on the initiation of call, means for variably adjusting a selected sender in response to impulses transmitted from the calling line, means controlled by the adjustment ofsaid sender for causing the trunk selecting switch of a wanted line to seize an idle trunk, means thereupon eiiective for causing the trunk selecting switch of the calling line to seize the same trunk, and means for effecting the release of said sender before the dis-establishment of the telephone connection.

12. In a telephone system, an incoming line, a plurality of outgoing lines, means including an automatic switch for extending said incoming line to a Wanted outgoing line, a sender for controlling the 0p eration of said automatic switch, means responsive to impulses over said incoming line for variably adjusting said sender, an operators position also arranged to control the setting of said automatic switch, means for signaling said operators position in response to the initiation of a call on said incoming line, and means for disabling said signaling means controlled by impulses over said incoming line.

13. In a telephone system, an incoming line,v aplurality of outgoing lines, means'ineluding an automatic switch for extending said incoming line to' a? wanted outgoing line, a sender selectively adjusted by impulses over said incoming line to control the setting of said automatic switch, means for connecting said sender to said incoming line, an operators position, and means for signaling said position when no impulses are transmitted to said sender after its seizure.

' 14. In a telephone system, an incoming r30 line, a plurality of senders, means for extending said incoming line to an idle sender, an operators position and a signal associated therewith, means for actuating said signal on the seizure of any of said senders, means controlled by the transmission of ini pulses over said incoming line tor disabling the actuatingmeans of said signal, and automatic means controlled by said sender for extending said incoming line to a desired outgoing line.

15. In a telephone system. an incoming line, a plurality of outgoing lines, an automatic switch for extending said incoming line to a desired outgoing line, subscriber controlled means including a register sender and operator controlled means for causing said automatic switch to extend said incoming line to a desired outgoing line, said sub scriber controlled means being normally effective to control the operation, a signal for indicating the necessity of using the open ator controlled means, and discriminating means for controlling said signal.

16. In a telephone system, a plurality of telephone lines, certain of said lines being provided with impulse transmitting devices, a register sender arranged to be variably controlled over a telephone line in response to the operation of said impulse transmitting device, means including automatic switches for interconnecting any one of said lines with any of the other lines, said automatic switches being controlled in accordance with the setting of said register sender, an operator controlled transmitting device for causing said automatic switches to interconnect a telephone line to any oi the other lines, and a signal for indicating that the operators transmitting device must be used in completing a connection, and means for disabling said signal.

17. In an automatic telephone system, a plurality of telephone lines, switches individual to each telephone line, a plurality ct trunk circuits accessible to each switch, a plurality of senders each comprising a. plurality of step by step register switches, means including the individual switch of a calling line for connecting said telephone line to an idle register sender and to an idle trunk circuit, means controlled over said lines for variably and selectively adjusting the selected register sender, a test circuit for each telephone line and means including the adjusted sender for controlling the completion of the test circuit to the called line to cause its individual line switch to complete a telephonic connection between the calling and called lines over a selected trunk circuit.

18. In an automatic telephone system, a plurality of telephone lines, a plurality of trunk circuits, progressively movable nonnumerical switches associated with said telephone lines for connecting the telephone lines to idle trunk circuits, a plurality of senders each comprising a plurality of step by step register switches, means for connecting a calling telephone line to an idle sender, said means including a non-numerical switch, means controlled over said telephone line for selectively and variably adjusting the register switches of a selected sender, a starting circuit for each telephone line for initiating the operation of the non-numerical switch associated with a line to seize a selected trunk circuit when it is called and means including the adjusted register sender for completing the starting circuit of the wanted line.

19. In a telephone system, a plurality of incoming circuits, aplurality of non-numerical switches each provided with fixed contacts, movable contacts cooperating therewith and separate operating means for the movable contacts of each switch, each incoming circuit terminating in the movable contacts of a non-numerical switch, a plurality of trunk circuits, the ends of each trunk circuit terminating in the fixed contacts of non-numerical switches and sender means each including rotary register switches for causing the switches associated with two incoming circuits to complete a telephonic connection between said last mentioned circuits over a selected trunk circuit.

20. In telephone system, a plurality of telephone lines, a plurality of non-numerical switches each provided with fixed contacts, movable contacts and separate operating means for each switch, trunk circuits terminating in said fixed contacts, each telcphone line terminating in the movable contacts of non-numerical switch, a plurality of senders each including a plurality of register switches arranged. to be adjusted in. succession and means including the call.- ing telephone line and the contacts of a. non-numerical switch for adjusting said register switches, a circuit completed under the control of said registers for causing the non-numerical switch associated with the called line to seize a trunk circuit and thereby complete a telephonic circuit between the calling and called lines through the non numerical switches associated with these lines,

21. In a telephone ystem, a plurality of telephone lines a trunk selecting switch as sociated with each of said lines, of trunk circuits terminating in said switches, a sender accessible to said. tele phone lines and including a plurality of register switches arranged to be variably controlled over a calling telephone line, means for causing the trunk selecting switch associated with the calling line to seize a trunk circuit, a test circuit for each telephone line, a group of relays common to said telea plurality phone lines and co-opeating with said register sender for completing the test circuit of the called line and means including said test circuit for causing the trunk selecting switch associated with the called line to seize a trunk circuit whereby the calling and called telephone lines may be telephonically connected to a trunk circuit by means of the trunk selecting switches associated with these telephone lines.

22. In an automatic telephone system, a plurality of incoming circuits, a non-numerical switch for each incoming circuit, trunk circuits terminating in said nonnumerical switches, means to cause a calling incoming circuit to seize an idle trunk circuit, a register sender common to said incoming circuits and including a plurality of rotatable switches arranged to be variably adjusted in succession over any of said incoming circuit to designate any other incoming circuit as a wanted incoming circuit, a plurality of starting circuits, a group of multi-contactrelays common to said incoming circuits and operating with said rotary switches to complete a starting circuit of a wanted incoming circuit and thereby cause the non-numerical switch of said wanted inecoming circuit to seize the selected trunk circuit.

In witness whereofll hereunto subscribe my name this 16th day of February, A. D. 1920.

XVINFRED T. POWVELL. 

